Patent GB-620298-A (GB)
Title: Improvements in or relating to cyclic process for the preparation of acetylenic alcohols
IPC: C07C29/42
Filed: 1944-11-03
Abstract: In a cyclic process for the production of acetylenic alcohols from 1-alkynes and aliphatic aldehydes having from 4 to 8 carbon atoms or aliphatic ketones with the aid of a finely divided suspension of potassium hydroxide in <PICT:0620298/III/1> an acetal or normally liquid polyether (see Group IV (b)), a mixture of an aqueous solution of potassium hydroxide and the acetal or polyether is dehydrated as shown in a kettle 1 with agitation, a water-acetal azeotrope being distilled off through packed column 6 and condenser 7, the condensate separating into two layers in decanter 9 from which the upper acetal layer is returned to the column.  Ultimately, the residue in the kettle comprises a two-phase liquid mixture of the acetal and potassium hydroxide.  This mixture is converted into a slurry in cooler 16, reacted with the alkyne in mixer 24 and then with the aldehyde or ketone in mixer 26 and finally treated with water in mixer 29. The resulting product comprising acetylenic alcohol, water, the acetal or polyether and potassium hydroxide is distilled in column 32 where a water-alcohol azeotrope is removed under a reduced pressure of 500 mms. or less, from which azeotrope the water may be removed by azeotropic distillation with benzene or other suitable liquid to give the pure acetylenic alcohol.  The residual mixture from column 32 comprising acetal and aqueous potassium hydroxide is withdrawn from callandria 35 and passed back via lines 46 and 13 and column 6 to the kettle for use in the succeeding cycle.  Alcohols prepared in this manner comprise 2-methyl-3-butyne-2-ol, 3-methyl-1-pentyne-3-ol, 2-methyl-3-pentyne-2-ol, 3-methyl-4-pentyne-3-ol, 1-hexyne-3-ol 3 : 5-dimethyl-1-hexyne-3-ol, 4-ethyl-1-octyne 3-ol, 1-nonyne-3-ol, 3-methyl-1-nonyne-3-ol and 6-ethyl-3-decyne-5-ol.  Suitable acetals or polyethers are 1 : 1-dibutoxyethane, ethylene glycol diethylether, diethylene glycol diethyl ether, 2 : 3-butanediol diethyl ether, 1 : 1-dibutoxy - 2 - ethyl - hexane, 1 : 1 - dipropoxy - butane, dibutoxy-phenyl-butane, 1 : 1-dibutoxy-butane, 1 : 1-dibutoxy-2-phenylethane, dimethoxymethane and 4 : 5-dimethyl-2-propyl-1 : 3-dioxolane.  The Specification as open to inspection under Sect. 91 is not limited to the use of the reduced pressure specified above in the removal of the water-alcohol azeotrope.  This subject-matter does not appear in the Specification as accepted.ALSO:<PICT:0620298/IV (b)/1> Acetylenic alcohols are prepared by a cyclic process which comprises introducing a 1-alkyne, having a terminal hydrogen atom in the 1-position, into a cooled finely-divided suspension of potassium hydroxide in an acetal or a normally liquid polyether, reacting the resulting mixture at a temperature not exceeding 90 DEG  C. with an aliphatic aldehyde having from 4 to 8 carbon atoms or an aliphatic ketone to produce the potassium derivative of the corresponding acetylenic alcohol, hydrolysing the latter to the parent alcohol by the addition of water to give a mixture of acetylenic alcohol, acetal or normally liquid polyether, water and potassium hydroxide, distilling off the alcohol in the form of its water azeotrope under an absolute pressure of 500 mm. or less, heating the resultant mixture of water, acetal or normally liquid polyether, and potassium hydroxide, distilling off as much as possible of the water from the mixture in the form of its azeotrope with acetal or polyether and returning the acetal or normally liquid polyether to the hot residue from the distillation consisting essentially of potassium hydroxide, until a two-phase liquid mixture of acetal or normally liquid polyether and potassium hydroxide is obtained, and thereafter cooling the mixture with agitation to produce a finely-divided suspension of potassium hydroxide in the acetal or polyether for use in a succeeding cycle. Thus, a mixture of acetal and an aqueous solution of potassium hydroxide is heated with agitation in a kettle 1, a water-acetal azeotrope being distilled off through a packed column 6 and condenser 7 and the condensate allowed to separate into two layers in a decanter 9 from which the upper acetal layer 11 is returned to the column 6 and the aqueous layer 10 is used in a later step.  The residue in the kettle comprising a two-phase liquid-mixture of acetal and potassium hydroxide containing about 13 per cent water is passed to a stirred cooler 16 where a potassium hydroxide-acetal slurry is obtained.  This slurry is pumped via cooler 21 to an orifice mixer 24 where it is intimately mixed at about -10 DEG  C. with a 1-alkyne introduced via valve 23.  The resulting mixture containing the potassium derivative of the 1-alkyne is passed to orifice-mixer 26 maintained at between -10 DEG  and +90 DEG  C., being mixed en route with a carbonyl compound introduced via valve 27.  The soformed potassium derivative of the corresponding acetylenic alcohol is then hydrolysed in orifice-mixer 29 by means of water supplied via line 15 from the decanter 9, additional water being added, if necessary, via 30.  The resulting free alcohol mixture is next distilled in column 32 where an alcohol-water azeotrope is removed under reduced pressure, pure alcohol being recovered from the distillate in receiver 41 by removing the water by azeotropic distillation with benzene or other suitable liquid.  The residual mixture in column 32, comprising potassium hydroxide, water and acetal, passes through a callandria 35 back to the kettle 1 via lines 46 and 13 and column 6 for use in the succeeding cycle. Examples illustrating this method comprise the preparation of (1) 2-methyl - 3 - butyne - 2 - ol from acetylene and acetone and (2) 3 : 5-dimethyl-1-hexyne-3-ol from acetylene and isobutyl methyl ketone, the solvent in both cases being 1 : 1-dibutoxyethane; (3) 1-hexyne-3-ol from acetylene and n-butyraldehyde using ethylene glycol diethylether, and (4) 3-methyl-1-pentyne-3-ol from acetylene and methyl ethyl ketone using 4 : 5-dimethyl-2-propyl-1 : 3-dioxolane as solvent.  The following alcohols may be prepared similarly: 2-methyl-3-pentyne-2-ol, 3-methyl-4-pentyne-3-ol, 4-ethyl-1-octyne-3-ol, 6-ethyl-3-decyne-5-ol, 1-nonyne-3-ol and 3-methyl-1-nonyne-3-ol. Additional reactants specified are propyne, 1-pentyne and phenyl acetylene, and n-hexaldehyde, n-heptaldehyde and 2-ethyl hexaldehyde. Other solvents mentioned are diethylene glycol diethyl ether, 2 : 3-butanediol diethyl ether, 1 : 1-dibutoxy-2-ethyl hexane, 1 : 1 - dipropoxybutane, dibutoxy - phenyl methane, 1 : 1-dibutoxybutane, 1 : 1-dibutoxy-2-phenylethane and dimethoxymethane.  Specification 544,221 is referred to.  The Specification as open to inspection under Sect. 91 is not limited as regards both the temperature at which the carbonyl compound is reacted with the alkyne and the reduced pressure at which the alcohol-water azeotrope is removed. This subject-matter does not appear in the Specification as accepted.